The present invention relates to a method and apparatus for removing a faulty weft on a loom, and more particularly relates to an improved system for performing removal of faulty weft and its preparatory operations in a fully automatic fashion on a loom.
Here, the term "a faulty weft" refers to a weft inserted in fault such as a short-pick weft, a nose-bent weft, a broken weft and a weft not correctly sensed by a weft feeler mechanism.
The term "next weft" refers to a weft incompletely inserted subsequent to insertion of a faulty weft due to inertia of loom crank rotation.
It is already known and practiced in various ways to remove a faulty weft from its shed in an automatic fashion when loom crank rotation is stopped on detection of abnormal weft insertion. One example is disclosed in Japanese Patent Opening No. Sho. 58-220856. The system of this earlier proposal is provided with a carriage which reciprocates in the weft direction over sheds in the vicinity of the cloth-fell. The carriage carries a releaser unit and a catcher unit for faulty wefts. When loom crank rotation is stopped due to abnormal weft insertion and the loom crank is rotated over almost one cycle opposite to the normal rotation in order to open the shed of a faulty weft, the point of a finger hanging from the releaser unit slides rearwards on the cloth in the warp direction and hooks the faulty weft at the cloth-fell in order to release it from the cloth-fell. Next, the catcher unit descends with its downward bar and a seat on the lower end of the bar receives the faulty weft released from the cloth-fell in order to clamp it in corporation with an adjacent support. Thereafter, as the catcher unit ascends, the clamped faulty weft in loop is partly taken out of the shed, by operation of a pair of rollers, through between warps forming the upper warp sheet. The operation is performed in an automatic fashion well sufficing the demand for automatization.
This system, however, is accompanied with several drawbacks. First, this system is involved in operations only which follow after the shed for the faulty weft is opened. In other words, the device is not involved in handling of the next weft at all. Automatic removal of the next weft may be completed by repeating twice the operations of the releaser and catcher units. Even when such a repeated operation is employed, the system is accompanied with further drawbacks. During loom crank rotation due to inertia the faulty weft is strongly beated against the cloth-fell by the reed and, as a consequence, is placed in tight contact with the cloth-fell even after its shed is opened. Therefore, it does not always reliably follow that the point of the finger falls between the faulty weft and the cloth-fell on arrival at the cloth-fell. That is, the faulty weft cannot be always reliably hooked by the finger. In order to avoid this failure, the point of the finger may be strongly urged downwards by suitable elastic means such as a spring. Then the finger may damage the clock inasmuch as the sharp point of the finger strongly scratches the cloth surface as it slides.
Even when the faulty weft is successfully released from the cloth-fell, the faulty weft has to be assigned to the seat of the catcher unit bar and clamped in corporation with the adjacent support. Since the faulty weft assumes a quite unstable position after release from the cloth-fell, it is highly difficult to successfully assign such as unstable faulty weft between such small cooperating members over twice. Even a small disturbance on the faulty weft during assignment would cause the faulty weft to fall from the members.
Thus, the system of the earlier proposal is directed to removal of a faulty weft only and preparatory operations such as removal of the next weft have to be carried out by a separate system or systems. In addition, its operation is quite unreliable. In order to raise the operational reliability, one must sacrifice other features such as cloth quality and small construction.